Innovative RF Device Technologies for Advanced Information and Communications Network Society

This paper describes the innovation of RF device technologies for wireless communication. Over the last decade, data traffic on the internet has increased exponentially. In particular, data traffic over wireless networks has exploded due to IoT including mobile phones. Since the 1990s, global wireless communication systems and personal cellular services, have evolved from 1G to 4G in order to meet the huge demand for wireless communication. Recently we are focusing on the research and development of devices and amplifiers for 5G, which is being implemented, and beyond 5G and 6G, which are on the horizon. The 5G system consists of many macro cells and small cells, and its power consumption is enormous. The high efficiency and high- power density of GaN devices decreases the power consumption of the whole system. Up to now, ongoing research on N-polar GaN has demonstrated an extremely high-power and high PAE at W-band. Recently we demonstrated innovative high-k MIS N-polar GaN HEMTs which were fabricated, for the first time, using commercial 4-inch wafer process facilities. We overcame the challenge of developing a vital gate insulating film by incorporating Si LSI material technology. Furthermore, a ScAlN/GaN HEMT with high polarization and lattice-matching is also promising. An AlN/GaN HEMT on AlN substrate achieves high current density without heating up. Heat dissipation technology is a critical method of improving device performance and efficiency. Moreover, we developed a novel passivation technology to control the electric flux lines using dielectric potions as a new engineering method for controlling the electric field of devices. This paper reports these innovative technologies for RF devices and amplifiers.